Crystal detector assembly



y 29, 1951 A. NOYES, JR 2,555,151 I CRYSTAL DETECTOR ASSEMBLY Filed July 1, 1948 Patented May 29, 1951 CRYSTAL DETECTOR ASSEMBLY Atherton Noyes, Jr., Mountain Lakes, N. J., as-

signor to Aircraft Radio Corporation, Boonton, N. J a corporation of New Jersey Application July 1, 1948, Serial No. 36,493

This invention relates to a crystal detector assembly and more particularly to an assembly adapted to be supported at the rear of the panel of an ultra-high frequency radio receiver and of such construction as to permit a ready removal and replacement of the crystal detector unit from the front of the panel.

Objects of the invention are to provide a crystal detector mounting assembly of coaxial line type which, when supported at the rear of a panel, permits removal and/ or replacement of the crystal detector unit from the front of the panel. An

object is to provide a crystal detector mounting assembly of coaxial line type having an input connection normal to the axis of the assembly and a coaxial line output connection at an end of the assembly. An object is to provide a crystal detector mounting assembly of coaxial line type in which the crystal detector unit is plugged into and axially removable from the assembly,

and in which the input circuit is connected to the tip of the crystal unit, and the output circuit is connected to the sleeve of the crystal unit. An-

other object is to provide a crystal detector mounting assembly to which the input and output circuits may be permanently connected, and

.a crystal unit may be inserted and removed without breaking those connections.

These and other objects and the advantages of the invention will be apparent from the following specification when taken with the accompanying drawing in which:

Fig. l is an axial section of a crystal detector mounting assembly constituting one form of the invention V Fig. 2 is a transverse section taken on line 2-2 of Fig. l; and

Fig. 3 is a perspective view of the outer coaxial conductor which forms a socket receptacle for a plug-in crystal detector unit.

In the drawings, the reference numeral iidentifies the cylindrical metal shell of the crystal detector assembly which is threaded at its opposite ends to receive a front closure cap 2 of metal and a gland nut 3 having an internal flange for securing a coaxial output cable connector 4 to the crystal detector assembly. The radio frequency input to the assembly is through a stud 5 which extends radially into and is insulated from shell i by a bushing t of polystyrene or 5 Claims. (01. 250-s1) her or waveguide, and the loop 8 is of course omit- 3 ted when the radio frequency input is byway of a coaxial cable connected to the elements 5 and 1. The stud 5 is threaded into the cylindrical head 9 of an inner conductor it which is located coaxially within and insulated from an outer conductor or sleeve H by an insulating washer I2 on the conductor It and a similar washer !2- which is seated between a metal washer; and the head 9 of conductor Ill. The stud 5 passes through a side hole in sleeve H and isinsulated therefrom by sleeve 6. The outer conductor H is contracted radially to provide a seat to which the forward edge of washer I2 is clamped when the rear end M of the conductive sleeve is spun over the washer 13 to anchor the conductor [0 within the sleeve.

The forward end of the inner conductor IE) is counterbored and slotted to form a spring-finger socket it for receiving the tip terminal l5 of a crystal detector unit of known type such as JAN 1N27. comprising a tube it of insulating material housing the crystal (shown schematically by conventional symbol D) and closed at its forward end by a metal sleeve ll which terminates in a radially projecting flange 18. The reduced diameter upon and establish electrical contact with .the sleeve terminal i! of the crystal detector unit.

.An intermediate portion of the reduced diameter section of conductive sleeve H is provided with indentations l9 which guide the unit for axial movement to seat the tip terminal It in the socket I0 at the forward end of conductor I0.

The sleeve terminal I? of the crystal detector unit may be short-eircuited to ground, i. e. to the shell I, for radio frequencies by a capacity .by-pass in the cap 2 or, as illustrated, by a sleeve 23 which has an axial length of a quarter wavelength, the forward flanged end of the sleeve being soldered to the shell I. The sleeve 20 is in- ;sulated from conductor H by an inner cylinder 2i of polystyrene, and is spaced radially inward from shell l by an outer polystyrene cylinder 22. The inverted U-shaped path from the sleeve te 'minal IT to the soldered junction of sleeve 20 and shell I is one-half wavelength; and the sleeve tershell I by the threaded connection of the radio frequency input stud 5 and the head 9 of the conductor It and by the snug fit of the cylindrical :conductorll within the in ulat n cy nde 2.-

electrically connected to washer l3 by a spring 26. The output circuit is thus connected between ground and the sleeve ll, whereas the radio frequency input circuit is connected between ground and the tip [5 of the crystal unit. A bushing 27 of glossy material such as :polyiron at the end of shell I prevents resonance effects in the output circuit at radio frequencies which might cause absorption of energy at certain frequencies.

In the assembly as shown, the crystalis used as a simple detector, with radio frequency energy from a single source applied to the crystal tip l5 and direct current, audio or video output energy taken from the sleeve [1. Of course the same type of construction is applicable to mixer crystals if a second radio frequency input connection similar to stud 5 is brought in through the .shell to terminal I ii for connection to a suit- .able local oscillator.

The crystal detector assembly is supported on the receiver chassis by appropriate means, not shown, with the forward end of the shell I extending into the opening 28 of the receiver panel P. The closure cap 2 is applied and removed from the front of panel P, and the crystal detector unit may therefore be readily plugged into and removed from the front of the panel.

It is to be understood that the invention is their ends adjacent the removable cap end .of

said shell in resilient sockets, a mounted crystal detector unit including a crystal detector connected between terminals adapted to seat within the respective sockets, said crystal detector unit being insertable into and removable from said shell and sockets upon removal of said metal cap from said shell, said shell and the outer coaxial conductor having lateral openings in radial alinement with each other and with the inner conductor of saidpair, a radio frequency input conductor extending through said lateral openings and electrically connected to the inner conductor of said pair, and an output conductor extending axially from the other end of said shell and elec vtrically connected to the other of the coaxial conductors of said pair.

2. A crystal detector assembly as recited in claim 1, in combination with means grounding the outer terminal of said crystal detector unit upon said shell for radio frequency.

3. A crystal detector assembly as recited in claim 2, wherein said means comprises a conductive sleeve having an axial length equal to one-quarter wavelength of aradio frequency wave to be imposed upon said radio frequency input opening,

conductor, insulating means supporting said conductive sleeve between and radially spaced from said shell and said outer conductor, said sleeve having a flanged end in radial alinement with said outer terminal of the crystal detector unit and connected electrically to said shell.

4. A socket assembly for receiving a crystal detector unit having a tip terminalat one end and a sleeve terminal at the other end; said socket :assembly comprising a cylindrical sleeve having an inner section of one diameter and an outer section of smaller diameter, the larger diameter section being provided with an opening through the wall thereof, a washer of insulating material within the larger diameter section of the sleeve, a cylindrical conductor extending through said washer and having an enlarged head seated against the inner face of the washer, said enlarged head being provided with a threaded bore transverse to the axis of said cylindrical conductona terminal extending through said opening of the sleeve and threaded into the bore of said enlarged head, a bushing of insulating material spacing said terminal from the sleeve, a second washer of insulating material within the larger diameter section of said sleeve and seating against said bushing and the inner face of the enlarged head of said cylindrical conductor, a metallic washer within said sleeve at the inner face of said second washer of insulating material, the inner end of said sleeve being inturned to clamp said washers and the cylindrical conductor within said sleeve, and the outer ends of said sleeve and said cylindrical conductor being slotted .and resilient to form seats for receiving the sleeve and tip terminals respectively of a crystal detector unit.

5..A socket assembly for receiving a crystal detector unit having a tip terminal at one end and a sleeve terminal at the other end; said :socket assembly comprising a cylindrical sleeve having an opening through the wall thereof adjacent its inner end, a washer of insulating material Within said sleeve and outwardly of said a cylindrical conductor extending through said washer and having an enlarged head seated against the inner face of said washer,

said enlarged head being provided with coupling means alined with the opening of said cylindrical sleeve, an input terminal extending through the opening of said sleeve and connected to said coupling means, a bushing of insulating material "spacing said terminal from said sleeve, a second washer of insulating material within said sleeve between the enlarged head of said cylindrical conductor and the inner end of said sleeve, a metal washer within said sleeve at the inner face of said secondwasher of insulating material, and means securing said washers and the cylindrical conductor within said sleeve, the outer ends of saidcylindrical conductor and said sleeve being slotted and resilient for receiving the sleeveand tip terminals respectively of a crystal detector unit.

A'I'HERTON NOYES, JR.

REFERENCES CITED The following references are of record in the file of'this patent:

UNITED STATES PATENTS Number Name Date 2,433,387 Mumford Dec. 30, 1947 r 2,456,305 Nelson Dec. 14,1948 

